This invention concerns a catalyzed carboxylic ester/acyl fluoride interchange reaction as a route to fluorinated mono- and diacyl fluorides.
Nothing found in the prior art discloses an interchange reaction of the type herein disclosed as a route to preparation of fluorinated mono- and diacyl fluorides. Typical prior art processes include the following: U.S. Pat. No. 4,151,200 discloses preparation of polyfluorodiacyl fluorides by reaction of perfluorolactone with a fluorocarbon epoxide such as hexafluoropropene oxide; Japanese Application 53/111,011 discloses preparation of polyfluorodiacyl fluorides by reaction of an .alpha.,.omega.-diiodopolyfluoroalkane with SO.sub.3 ; Japanese Application No. 53/040,708 discloses preparation of fluorinated ester-acyl fluorides from diacyl fluorides; U.S. Pat. No. 3,250,807 discloses preparation of diacyl fluorides of fluorocarbon ethers by reaction of a perfluroinated diacyl fluoride such as oxalyl fluoride or difluoromalonyl fluoride with hexafluoropropene oxide.
In addition, U.S. patent application Ser. No. 071,684, now abandoned, discloses preparation of difluoromalonyl fluoride by reacting 3-methoxytetrafluoropropionyl fluoride with TiF.sub.4 or SbF.sub.5. Fear et al., in J. Appl. Chem., 5, 589 (1955), describe preparation of difluoromalonic acid and its reaction with phosphorus oxychloride to give difluoromalonyl chloride.
Fawcett et al, in J. Amer. Chem. Soc., 84, 4280 (1962), disclose preparation of 3-methoxy tetrafluoropropionyl fluoride from methyl trifluorovinyl ether by reaction with carbonyl fluoride; Lovelace et al, in "Aliphatic Fluoride Compounds", ACS Monograph Series No. 138, 219 to 228 (1958) and Hudlicky, in "Chemistry of Organic Fluoride Compounds", MacMillan, 151 (1961), disclose several methods of preparing fluorinated monoacyl fluorides, most commonly by heating the corresponding acyl chlorides with a metal fluoride such as KF or SbF.sub.3.
Olah, et al., in Science, 206 (4414), 13 (1979), describe the addition of hydrofluoric or fluorosulfonic acids to the known Lewis acid fluorides; SbF.sub.5, TaF.sub.5, NbF.sub.5, AsF.sub.5 or BF.sub.3, especially SbF.sub.5, to produce "superacid" systems of high catalytic activity. Highest acidity is said to be achieved in the HF-SbF.sub.5 system.
Howells and McCown, Chem. Revs., 77 (1), 69 (1977); and Yakobson and Furin, Synthesis, 1980 (5), 345, also describe highly acidic catalytic mixtures of fluorosulfonic or hydrofluoric acids with SbF.sub.5 ; highest acidity is ascribed to the HSO.sub.3 F-SbF.sub.5 system. Howells and McCown also disclose highly acidic mixtures of SbF.sub.5 or TaF.sub.5 with trifluoromethane sulfonic acid.